The goal of this project is to characterize and isolate human lymphocyte subpopulations and evalute the function of such populations in the immune response in both normals and disease states. Lymphocyte subpopulations are isolated and, both before and after various procedures, are evaluated for surface Ig and the receptor for complexed antibody (primarily B cell markers). Isolated subpopulations of lymphoid cells and clonal populations from disease states will be used to develop reagents specific for each subpopulation.